The present invention relates to a remote control system of an optical repeater for the transmission of a digital signal so that the operation of each optical repeater is controlled at terminal stations installed at the extreme ends of the optical fiber cable.
In an optical communication system utilizing optical repeaters inserted in an optical fiber cable, the operational reliability of components in an optical repeater is not high, and so a redundant arrangement of components in an optical repeater must be adopted, so that when there is something wrong with the particular component the switching is effected to one of the standby components. Also, an optical repeater has many switches for composing a return path so that a terminal station can close that return path and test the operation of each repeater by transmitting a test signal and receiving the same through that return path.
Accordingly, each of the switches installed in each repeater must be controlled remotely from a terminal station individually in order to test and/or replace a component and/or a repeater itself.
A prior remote control system of an optical repeater utilizes an interstitial cable which is installed along a communication cable for transmitting a control signal. However, that interstitial cable system has the disadvantage that the price of a cable is high and the structure of a cable is complicated. Further, a prior remote control system transmits the control signal in a digital form with high transmission speed. Therefore, when there is a noise in a communication line, and that control signal has a transmission error, the wrong control is performed. Thus, the operational reliability of the control is not high.